This invention relates to rotary machine technology and specifically, to a discrete compressor bleed manifold attachable to the associated compressor case.
Reducing radial clearance between rotating compressor blades and the compressor case in axial flow industrial gas turbines is essential for improved performance. Current industrial gas turbine compressor bleed manifolds are integral to the basic compressor case structure. In other words, the current industrial turbine case design philosophy integrates the bleed manifold with the compressor case. This arrangement is not conducive to reducing compressor clearance, however, because the single shell or case is required to carry the engine loads and to maintain a round, tight clearance flow path. Such manifolds typically include opposed manifold sections joined along axially extending, opposed vertical flanges by a plurality of transversely oriented bolts. These bolts are necessarily far removed in a radial direction from the flow path, particularly at the radially inner manifold inlet. The current compressor bleed manifold structure further increases the challenge to good case design by disrupting an otherwise smooth load path; creating unsupported case wall sections which lead to the so-called “diving board” effect; limiting extraction pipe locations and resultant loads into the case; and creating thermal response mismatches between the rotor and the case.
A commonly owned pending application Ser. No. 10/920,166 filed Aug. 18, 2004 entitled “Compressor Bleed Air Manifold for Blade Clearance Control” addresses similar problems with split bleed manifolds by circumferentially extending, vertical flanges.